I have a Chromecast with Google TV (4K) that works as a streaming device when using the internal TV speakers. For our preferred audio, we have a full SONOS surround sound system (SONOS Arc soundbar, Sub Gen 3 subwoofer, 2x Era 100 rear speakers) that works perfectly with any regular streaming of music etc. from phones. However, it will often not work at all with the Chromecast. Despite all speakers being installed and paired properly, the Chromecast will instead often use the TV's internal speakers. There are times that yes, the whole system works as desired. Other times it won't work, and I will then unplug the Chromecast, leave it 30 seconds, then plug it back in and the problem has gone away temporarily (sometimes having to repeat a couple of times). This is a VERY frustrating problem to be facing in 2024, especially when needing to try to unplug from a slim wall-mounted TV and plug back in.

I do believe that this is a Chromecast problem rather than a SONOS problem: there are enough posts across platforms backing this up (e.g. https://www.reddit.com/r/sonos/comments/13dlcvs/sonos_chromecast_with_google_tv_no_sound_half_of/).  However, Google support is terrible, and I’ve reached a point where the person (granted unpaid volunteer) advising me on the problem will not send further advice unless I ask around SONOS support.

So: is anyone else here facing the same problem? Is there a fix, or at least a less annoying workaround?

Further details: it's a JVC 55" 4K UHD TV (unsure or model number) with the SONOS Arc plugged into HDMI1-ARC, and the Chromecast plugged into HDMI3 (I’ve tried the other ports too). The Chromecast is fully up-to-date (OS version 12, security patch 1 April 2024, Kernel version 4.9.269). HDMI-CEC is enabled on the TV and on the Chromecast.

Thanks.